Currently, there are many hand tools need to know the twisting force of the tool applied to an object so that the user can well control the operation of the tool. Thereby there are many tools which are equipped with the twisting force measuring tool. In one prior art, a measuring rod interconnected to the driving head so that when the driving head is driven, the measuring rod will displace so that the twisting force can be got from the displacement of the measuring rod.
In another prior art, springs and rolling shafts are embedded into the handle of an open ended spanner so as to achieve the object of measuring the twisting force.
In above two prior arts, the structure is complicated and thus the cost is high and the assembly work is laborious. Thereby it is necessary to be improved.
Thereby electronic twisting force measurement devices are developed. One is the electronic twisting force measuring spanner, wherein a bridge circuit strain gauge is developed for sensing the deformation of the spanner. The strain gauge has a preferred effect to sense the twisting force, but the strain gauge is expensive so that this kind of prior art can be not widely accepted.